UNITED NATIONS — U.S. Secretary of State Antony Blinken called on every U.N. Security Council member to “send a clear message” to Russia that it must stop its nuclear threats in the war in Ukraine.

Russian President Vladimir Putin said earlier this week that his nuclear-armed country “certainly use all means available to us” if its territory is threatened and to defend the country and its people.

Blinken used a council session Thursday to criticize Russia’s invasion and press other countries to join in their forceful condemnations of the conflict.

“Every council member should send a clear message that these reckless nuclear threats must stop immediately,” he said.

A day after President Joe Biden assailed Russian leader Vladimir Putin for what he called egregious violations of the U.N. Charter and international law, the U.S. made the case at the U.N. Security Council that Russia should face further censure and isolation for its invasion.

Blinken Lists War Crime and Atrocity Allegations

Blinken listed several allegations of war crimes and other atrocities and called on countries that have yet to speak out forcefully against them as an affront to international order.

As the meeting began, there were already signs of a charged atmosphere around the council’s famous horseshoe-shaped table.

Ukrainian Foreign Minister Dmytro Kuleba wryly told reporters beforehand that he planned to keep a “safe social distance” from his counterpart Sergey Lavrov.

And as council staffers prepared to put a placard marking Ukraine’s seat next to Russia’s, Kuleba apparently raised objections — the placard was moved to another spot. Lavrov was not in the room at that point.

Despite Blinken’s forceful words, however, a U.S. official said the diplomat was under no illusion that the council would act against Russia, given its veto power as a permanent member. The official spoke on condition of anonymity ahead of Blinken’s speech in order to preview it.

Instead, the official said the aim is to convince other members to impress upon Moscow the global damage that the war is causing and demand that it end.

No Charges Yet in Ukraine War

The International Criminal Court opened an investigation in March into possible crimes amid the war and sent teams to gather evidence. Prosecutor Karim Khan told the council Thursday that he’s dispatching more ICC staffers next week to look into allegations emerging from eastern Ukraine.

Khan hasn’t yet announced any charges linked to the conflict, but he reiterated to the council that he believes there are reasonable grounds to think that crimes have been committed.

“The picture that I’ve seen so far is troubling indeed,” he said.

Ukraine, meanwhile, has been pushing for the creation of a special tribunal to prosecute alleged war crimes.

On Wednesday, Ukraine’s president laid out a detailed case against Russia’s invasion at the United Nations and demanded punishment from world leaders in a speech delivered just hours after Moscow made an extraordinary announcement that it would mobilize some reservists for the war effort.

Volodymyr Zelenskyy vowed in a video address to world leaders that his forces would not stop until they had reclaimed all of Ukraine.

“We can return the Ukrainian flag to our entire territory. We can do it with the force of arms,” Zelenskyy said. “But we need time.”